<html>
<head>
  <style>
    body { padding: 20px }
    h1 { font-size: 20px }
  </style>
  <style>
    p { background-color: #f00 }
  </style>
</head>
<body style="background: #ccc; padding: 40px">
  <h1 style="margin-top: 20px; background: #f00">Hello</h1>
  <p style="box-shadow: 0 0 10px #0008; padding: 20px; border: 1px solid #ccc; border-radius: 10px">Lorem ipsum dolor sit amet consectetur adipisicing elit. Repellat laudantium eius earum. Consequuntur, cupiditate ea aspernatur est maxime deserunt maiores nemo nulla, minima nesciunt praesentium. Voluptas, maxime beatae! Veniam, numquam!</p>

  <script>
    setInterval(() => document.querySelector('h1').textContent += ' hello', 100)
  </script>
</body>
</html>
